Typically, equipment designed for normal operation and for high pressures and high temperatures that is used in the oil and gas industry, requires sealing. As new seals are developed in the oil and gas industry to handle higher pressures and higher temperatures, the application of these seals can lead to issues on the overall design of the equipment. Usually internal grooves are machined allowing the assembly of soft seal materials, such as o-rings. However, when installing a tougher more robust seal, more space is typically required to lock the parts together. The size and assembly of the equipment that may result can present challenges in the design of the seal.
On certain types of equipment, such as valves, wellheads, subsea christmas trees, tubing spools, or production adapter bases, there may be issues related to the assembly condition of radial seals due to size constraints and load capacities. In a valve bonnet or in a wellhead, for example, a first seal may be installed within a packing gland or wellhead housing. A second seal or backup seal may also typically be installed that is separate from the first seal below. To keep the seal separate, a locking device is installed within the valve bonnet to hold the first seal in place while providing a shoulder or rim for the second seal or backup seal to land. A progressive drilled system is typically used to machine the internal portion of the bonnet or wellhead as this typically works well with soft materials. The locking device thus maintains the first seal in place and provides the second seal a shoulder on which to land.
However, in the design described above, separate parts are typically threaded together to form a seal groove and to allow for installation of the locking device. This can lead to secondary leak paths in the sealing system. To attempt avoidance of the secondary leak path, sealing systems are usually designed with larger bores and sizes. Maintaining the same size for lower and upper seals however is difficult without introducing additional leak paths that allow for installation. In certain oil and gas applications, this secondary leak path can be an issue, especially when sealing production fluids and gases. The larger bores lead to larger and heavier equipment which is also costlier.
A need exists for a technique to minimize the bore size of equipment via an improved locking device.